Commercial or institutional kitchens generally include cook stoves, hot plates, deep fat fryers, and other cooking devices that produce heat energy and particulates, i.e. grease. The extreme heat and particulates must be exhausted to atmosphere usually through flue chimneys or similar venting devices for the safety and comfort of the kitchen workers. This process replaces the hot kitchen air with cooler, clean outside air. Although this circulation process is necessary to provide a constant source of clean air to the kitchen environment, it is inefficient and uneconomical, especially in colder climates where the cost to heat internal air and water is significant.
Another problem encountered in commercial kitchens is that the generated particulates must be filtered. The particulates, that most commonly includes grease can eventually cause malfunction of air ventilation systems, which may create fire hazards. Accordingly, air filters located in flume hoods positioned over cooking surfaces must be cleaned often, which is time-consuming and expensive.
Venting and filtering systems may employ heat exchangers to capture thermal energy from the hot gases. For example, some systems employ a heat exchanger positioned downstream of a grease filter. This configuration is unfavorable for many reasons. First, these designs may be inefficient as the heat exchanger is usually located a significant distance from the heat source, which means heat is lost before the hot air encounters the heat exchanger. That is, the thermal energy is lost through heat dissipation before the heat exchanger is reached. Second, the existing grease filters significantly impede air flow, especially when congested with grease, which reduces the efficiency of the air ventilation system as heat is absorbed by the filter before the hot air reaches the heat exchanger. Third, when the heat source is turned off, the grease quickly solidifies within existing filters, which usually include fins that capture and maintains the particulate matter.
Many existing kitchens fail to incorporate any kind of heat exchanger because of integration costs. Retrofitting existing kitchen equipment with heat exchanger systems may require an entirely new flue hood assembly and substantial piping and accessories. Thus, conversion is time-consuming and expensive.
While some improvements have been made to combine a filter and heat exchanger, such as disclosed in U.S. Pat. No. 5,456,244, there remains a need to provide a filter system of simplified construction and that provides more efficient heat transfer than existing devices. To address this long-felt need, one embodiment of the present invention is a system for filtering and heat capture that is efficient and that may be retrofitted into existing flue systems.